In TOW the Halliwell's go to the future, future Prue is on the couch flipping through the Book of Shadows while future Piper is looking on. Well, in a previous slip-up, someone said that the "Return Spell" is right there in the front of her. Well, that is the first slip-up. The next one is when the camera is looking at the book as Prue is flipping through it, you see her pass by the "Create a Door" spell... a couple of seconds later, Prue goes back to it a finds the map of the prison that Phoebe was in. It wasn't there before, did it just magically appear....???? hmmmm.... and the next slip-up is when Prue is telling Piper "Look there's a spell to create money... uh... to bend someone's will.." ((or something like that)) well, when she says that she is looking at two pages (meaning one spell is on the left and the other is on the right" well if you look closely at the book... the left side is blank and the other side is the "Return Spell" Jeez... There's a lot of slip-ups here!